Published: September 18, 2012

BOSTON — If you grab the hand of a two-armed robot named Baxter, it will turn its head and a pair of cartoon eyes — displayed on a tablet-size computer-screen “face” — will peer at you with interest. Go to the article to see this.

REFINEMENT IN MOTION: Robotics designers seek to have their machines emulate human gestures and positions.

The sensation that Baxter conveys is not creepy, but benign, perhaps even disarmingly friendly. And that is intentional.

Baxter, the first product of Rethink Robotics, an ambitious start-up company in a revived manufacturing district here, is a significant bet that robots in the future will work directly with humans in the workplace.

That is a marked shift from today’s machines, which are kept safely isolated from humans, either inside glass cages or behind laser-controlled “light curtains,” because they move with Terminator-like speed and accuracy and could flatten any human they encountered.

By contrast, Baxter, which comes encased in plastic and has a nine-foot “wingspan,” is relatively slow and imprecise in the way it moves. And it has an elaborate array of safety mechanisms and sensors to protect the human workers it assists.

Here in a brick factory that was once one of the first electrified manufacturing sites in New England, Rodney A. Brooks, the legendary roboticist who is Rethink’s founder, proves its safety by placing his head in the path of Baxter’s arm while it moves objects on an assembly line.

The arm senses his head and abruptly stops moving with a soft clunk. Dr. Brooks, unfazed, points out that the arm is what roboticists call “compliant”: intended to sense unexpected obstacles and adjust itself accordingly.

The $22,000 robot that Rethink will begin selling in October is the clearest evidence yet that robotics is more than a laboratory curiosity or a tool only for large companies with vast amounts of capital. The company is betting it can broaden the market for robots by selling an inexpensive machine that can collaborate with human workers, the way the computer industry took off in the 1980s when the prices of PCs fell sharply and people without programming experience could start using them right out of the box.

“It feels like a true Macintosh moment for the robot world,” said Tony Fadell, the former Apple executive who oversaw the development of the iPod and the iPhone.

Baxter will come equipped with a library of simple tasks, or behaviors — for example, a “common sense” capability to recognize it must have an object in its hand before it can move and release it.

Although it will be possible to program Baxter, the Rethink designers avoid the term. Instead they talk about “training by demonstration.” For example, to pick up an object and move it, a human will instruct the robot by physically moving its arm and making it grab the object.

The robot’s redundant layers of safety mechanisms include a crown of sonar sensors ringing its head that automatically slows its movements whenever a human approaches. Its computer-screen face turns red to let workers know that it is aware of their presence.

And each robot has a large red “e-stop” button, causing immediate shutdown, even though Dr. Brooks says it is about as necessary as the Locomotive Acts, the 19th-century British laws requiring that early automobiles be preceded by a walker waving a red flag.

Soon, Dr. Brooks predicts, robots will be mingling with humans, routinely and safely. “With the current standards, we have to have it,” he said of the e-stop button. “But at some point we have to get over it.”

What kind of work will Baxter and its ilk perform? Rethink, which is manufacturing Baxter in New Hampshire, has secretly tested prototypes at a handful of small companies around the country where manufacturing and assembly involve repetitive tasks. It estimates that the robots can work for the equivalent of about $4 an hour.

“It fit in with our stable of equipment and augmented the robots we already have,” said Chris Budnick, president of Vanguard Plastics, a 30-person company in Southington, Conn., that makes custom-molded components.

Employees whose menial tasks are done by robots are not being laid off, he said, but assigned to jobs that require higher-level skills — including training the robots to work on manufacturing lines with short production runs where the tasks change frequently.

“Our folks loved it and they felt very comfortable with it,” Mr. Budnick said. “Even the older folks didn’t perceive it as a threat.”

Other efforts are under way to design robots that interact safely with human workers.Universal Robots, a Danish firm, has introduced a robot arm that does not need to be put in a glass cage — though the system requires a skilled programmer to operate.

And late last year Javier Movellan, director of the Machine Perception Laboratory at the University of California, San Diego, traveled to Tijuana, Mexico, where he took videos of workers in factories where jobs have been outsourced from the United States.

He wanted to study how the workers used their hands in an array of tasks, from woodworking to making automobile parts. After he returned to the United States, Mr. Movellan analyzed the videos with other scientists and realized that assembly workers used their hands in ways fundamentally different from those of today’s grasping robots.

“For humans it is very difficult to repeat the same movement twice,” Mr. Movellan said. “If they grasp an object, they will do it differently each time.”

In contrast to the fixed repetitive tasks performed by today’s robot arms and hands, scientists at the University of California, San Diego, and the University of Washington have built several prototype hands with pliable fingers that can move as quickly as the humans’.

The research group has set up collaborative arrangements with the Mexican factories, known as maquiladoras where they will be able to test their new robots.

“Despite decades of automation, there are relatively few types of tasks that have been automated,” said Emanuel Todorov, a cognitive scientist at Washington.

This is now changing rapidly as a new wave of manufacturing robots appears, driven by the collapsing cost of computing and the rapid emergence of inexpensive sensors that give robots new powers of vision and touch.

“The big hot button in the robotics industry is to get people and robots to work together,” said David Bourne, a roboticist at Carnegie Mellon University. “The big push is to make robots safe for people to work around.”

Rethink itself has made a significant effort to design a robot that mimics biological systems. The concept is called behavioral robotics, a design approach that was pioneered by Dr. Brooks in the 1990s and was used by NASA to build an early generation of vehicles that explored Mars.

Dr. Brooks first proposed the idea in 1989 in a paper titled“Fast, Cheap and Out of Control: A Robot Invasion of the Solar System.” Rather than sending a costly system that had a traditional and expensive artificial intelligence based control system, fleets of inexpensive systems could explore like insects. It helped lead to Sojourner, an early Mars vehicle.

The next generation of robots will increasingly function as assistants to human workers, freeing them for functions like planning, design and troubleshooting.

Rethink’s strategy calls for the robot to double as a “platform,” a computerized system that other developers can add both hardware devices and software applications for particular purposes. It is based on open-source software efforts — including the Robot Operating System, or ROS, developed by the Silicon Valley company Willow Garage, and a separate project called OpenCV, or Open Source Computer Vision Library.

That will make it possible for independent developers to extend the system in directions that Rethink hasn’t considered, much in the same way the original Apple II computer had slots for additional peripheral cards.

“We will publish an interface for the end of the wrist,” Dr. Brooks said. That will mean that while Baxter comes with a simple hand, or “end effector,” it will be able to adapt the system with more complex and capable hands that will be able to perform tasks that require greater dexterity.